Wood fibers are the building blocks of paper and pulp products. Typically, properties of fibers, especially chemical properties, are measured on a macroscopic pulp sample that contains millions of fibers. While this information is essential to run unit operations in the mill, it is not sufficient to produce a final product with optimal properties. To truly optimize the performance in the pulp and paper mill requires that critical properties be measured on the single fiber level. With single fiber measurements, the uniformity (as well as the average values) of critical variables may be optimized and controlled. The result will be a globally optimized product that will have superior performance over that product which is controlled only by using averages of critical properties.
Instruments are available on the market today that can measure the geometric properties of single pulp fibers. These instruments can measure fiber length, coarseness, and fiber shape. In addition, some claim to be able to measure cell wall thickness. Mills routinely use these analyzer to assess and optimize the fiber's geometric properties to make the grade of paper currently being produced on their paper machine. Mills typically have fiber geometry specifications that include both average fiber properties as well as something about the uniformity of that fiber property.
An object of the present invention is to provide an apparatus and method that can measure fiber geometry characteristics, both the averages and the distributions, and critical chemical properties of the single fibers, such as lignin content (kappa number) or fiber charge. There is no instrument presently available that can measure this full suite of important fiber properties. It is also an object of the present invention to provide an apparatus and method by which paper makers will be able to correlate single fiber properties, such as comparing the relation between Kappa number and fiber shape, and, most importantly, develop relationships that allow them to determine the original profile of fiber properties and produce desirable grades of paper on their paper machine.